Controlling the volume fraction of glass-forming colloidal suspensions using thermosensitive host `mesogels'
| Autor: | Behra, J. S., Thiriez, A., Truzzolillo, D., Ramos, L., Cipelletti, L. |
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| Rok vydání: | 2022 |
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| Druh dokumentu: | Working Paper |
| DOI: | 10.1063/5.0086822 |
| Popis: | The key parameter controlling the glass transition of colloidal suspensions is $\varphi$, the fraction of the sample volume occupied by the particles. Unfortunately, changing $\varphi$ by varying an external parameter, \textit{e.g.} temperature $T$ as in molecular glass formers, is not possible, unless one uses thermosensitive colloidal particles, like the popular poly(N-isopropylacrylamide) (PNiPAM) microgels. These however have several drawbacks, including high deformability, osmotic deswelling and interpenetration, which complicate their use as a model system to study the colloidal glass transition. Here, we propose a new system consisting of a colloidal suspension of non-deformable spherical silica nanoparticles, in which PNiPAM hydrogel spheres of ~$100-200 \mu m$ size are suspended. These non-colloidal `mesogels' allow for controlling the sample volume effectively available to the silica nanoparticles and hence their $\varphi$, thanks to the $T$-induced change in mesogels volume. Using optical microscopy, we first show that the mesogels retain their ability to change size with $T$ when suspended in Ludox suspensions, similarly as in water. We then show that their size is independent of the sample thermal history, such that a well-defined, reversible relationship between $T$ and $\varphi$ may be established. Finally, we use space-resolved dynamic light scattering to demonstrate that, upon varying $T$, our system exhibits a broad range of dynamical behaviors across the glass transition and beyond, comparable with those exhibited by a series of distinct silica nanoparticle suspensions of various $\varphi$. Comment: The following article has been accepted by The Journal of Chemical Physics. After it is published, it will be found at https://publishing.aip.org/resources/librarians/products/journals/ Copyright (2022) J.S. Behra, A. Thiriez, D. Truzzolillo, L. Ramos, L. Cipelletti. This article is distributed under a Creative Commons Attribution (CC BY) License |
| Databáze: | arXiv |
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